Film forming apparatus

ABSTRACT

A film-forming apparatus of the invention is a film-forming apparatus that includes: a processing container that defines a chamber, a pedestal arranged in the chamber, on which a substrate to be processed can be placed, a showerhead provided opposite to the pedestal, which has a large number of gas-discharging holes, a gas-supplying mechanism that supplies a process gas into the chamber through the showerhead, and a showerhead-temperature controlling unit that controls a temperature of the showerhead.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of Ser. No. 10/467,293, filed Aug. 7,2003, which is the National Stage of International ApplicationPCT/JP02/01110 filed on Feb. 8, 2002 in the Japanese language, andclaims the benefit of JP 2001-034520 filed Feb. 9, 2001, whichapplications are incorporated herein by reference.

This application is also a continuation of U.S. patent application Ser.No. 12/404,878 filed Mar. 16, 2009, which is a continuation of U.S. Ser.No. 11/727,485 filed Mar. 27, 2007, now abandoned, which is a divisionalapplication of U.S. Ser. No. 10/467,293 filed Aug. 7, 2003 which is anational stage application of PCT/JP02/01110 filed Feb. 8, 2002 in theJapanese language and claims the benefit of JP 2001-034520 filed Feb. 9,2001, each of which are incorporated herein in its entirety.

FIELD OF THE INVENTION

This invention relates to a film-forming apparatus that forms apredetermined thin film onto a substrate to be processed by means ofchemical vapor deposition process (CVD).

BACKGROUND ART

In a semiconductor-device manufacturing process, in order to fill holesbetween electric wirings formed on a semiconductor wafer as an object tobe processed, or in order to provide barrier layers, a metal such as Ti,Al or Cu and/or a metal compound such as WSi, TiN or TiSi is depositedto form a thin film.

Conventionally, such thin film of the metal or metal compound isdeposited by means of physical vapor deposition process (PVD). However,recently, it is requested to make devices micro and highly integrated,so that design-rule is especially severe. Thus, it is difficult toobtain sufficient properties by PVD, which is inferior in fillingperformance. Then, such thin film starts to be deposited by CVD, whichwe can expect forms a film of better quality.

As a conventional CVD film-forming apparatus, an apparatus for forming aTi film is explained as an example. In the CVD film-forming apparatusfor forming a Ti film, a pedestal, in which a heater is embedded andonto which a semiconductor wafer is placed, is arranged in a chamberhaving another heater. A showerhead for discharging a process gas isprovided above and opposite to the pedestal. The chamber is heated to apredetermined temperature, and the inside of the chamber is vacuumed toa predetermined vacuum level. Then, the semiconductor wafer placed onthe pedestal is heated to a predetermined temperature, while the processgas such as TiCl₄, H₂ and the like is supplied from the showerhead. Inaddition, a high-frequency electric power is applied to the showerhead,so that the process gas is changed to plasma thereof. Then, thefilm-forming process is conducted.

However, recently, the semiconductor wafer starts to be enlarged to 300mm. Thus, the film-forming apparatus has to be enlarged correspondingly.Therefore, the following problems appear manifestly.

When the temperature of the heater embedded in the pedestal rises up,the showerhead provided opposed to the pedestal is heated by radiantheat thereof. However, when the unit is enlarged, the showerhead is alsoenlarged, that is, heat capacity thereof becomes larger, so that ittakes a longer time for the temperature to become stable when theshowerhead is heated. That is, the throughput is deteriorated. If thetemperature of the showerhead, that is, the surface temperature of theshowerhead is not stable during a process, the process is not uniformlyconducted. In addition, the conventional showerhead has a structure withhigh heat-insulating properties, in order to secure temperaturestability during a process. Thus, if the showerhead is enlarged, ittakes also a longer time to lower the temperature to a predeterminedtemperature, for example for a cleaning process. If the cleaning processis conducted under a high-temperature state, the showerhead member maybe damaged.

In addition, during an idling state, the temperature of the pedestal hasto be set higher than that during the process, in order to maintain thetemperature of the showerhead at a predetermined temperature. This isexplained in detail. Conventionally, during the plasma process, thetemperatures of members in the chamber are raised by the plasma.Especially, the surface temperature of the showerhead tends to be raisedbecause it has a large area opposed to the wafer surface and exposed tothe plasma. However, when a film-forming process is conducted after anidling state or a cleaning process, it is possible that a film-formingrate for the first wafer is low. It is thought that the reason is thatthe temperature of the showerhead is low. That is, the temperaturethereof is about 500° C. during a normal film-forming process, but it isthought that the temperature falls down by about 20 to 30° C. In orderto prevent this, during the idling state or the cleaning process, thetemperature of the pedestal had to be set higher than the film-formingtemperature.

Furthermore, conventionally, at a maintenance process of the showerhead,an upper lid including the showerhead is opened by a degree not largerthan 90 degrees, and then the showerhead is removed or the like.However, as the film-forming apparatus is enlarged, when the showerheadis also bulked or enlarged, it is difficult to conduct the maintenanceprocess of the showerhead in accordance with the conventional method.

SUMMARY OF THE INVENTION

This invention is intended to solve the above problems. The object ofthis invention is to provide a film-forming apparatus that can lead ashowerhead to a predetermined temperature within a short time andwherein temperature stability of the showerhead is high, and to providea film-forming apparatus wherein maintenance of the showerhead can beeasily conducted.

This invention is a film-forming apparatus comprising: a processingcontainer that defines a chamber; a pedestal arranged in the chamber, onwhich a substrate to be processed can be placed; a showerhead providedopposite to the pedestal, which has a large number of gas-dischargingholes; a gas-supplying mechanism that supplies a process gas into thechamber through the showerhead; and a showerhead-temperature controllingunit that controls a temperature of the showerhead.

According to the invention, since the showerhead is provided with thetemperature controlling unit, the showerhead can be actively controlledto a desired temperature, when the showerhead is heated. Thus, even ifthe film-forming apparatus is larger, the temperature of the showerheadcan be raised and lowered within a short time. In addition, by activelycontrolling the temperature of the showerhead, temperature stability ofthe showerhead can be enhanced.

Furthermore, for example in a case of Ti-film-forming apparatus, when apre-coated film is formed on the showerhead or the like before a processto the substrate to be processed, or when a Ti film is formed on thesubstrate to be processed, the film is also formed (deposited) on asurface of the showerhead. At that time, in order to form a stable filmon the surface of the showerhead, Ticl_(x), which is generated by anintermediate reaction, has to be volatilized. Thus, the showerhead hasto be heated over 425° C., in particular over 500° C. In a conventionalart, it takes a long time to heat the showerhead, and it is uncertainwhether the showerhead is at a desired temperature, so that such astable film may not be generated. However, by providing thetemperature-controlling unit in the showerhead, the showerhead can becontrolled to a desired temperature during a film-forming process or apre-coating process, so that a stable film can be surely formed on theshowerhead. Therefore, the first film-forming process can be stablyconducted.

Preferably, the processing container is formed in such a manner that theprocessing container can be vacuumed.

In addition, preferably, the film-forming apparatus further comprises aheating unit that heats the pedestal.

In addition, preferably, the showerhead has: a chamber-inside part thatincludes a surface in which the large number of gas-discharging holesappear; and an atmosphere-side part that contacts with atmospheric airoutside the chamber; and the showerhead-temperature controlling unit isprovided in the atmosphere-side part.

In the case, the showerhead-temperature controlling unit can be handledin the atmospheric air.

In addition, preferably, the film-forming apparatus further comprises asecond heating unit that heats the chamber.

In addition, preferably, the showerhead-temperature controlling unitincludes: a heating mechanism that heats the showerhead; a coolingmechanism that cools the showerhead; a temperature-detecting mechanismthat detects a temperature of the showerhead; and a controller thatcontrols at least the heating mechanism, based on a result detected bythe temperature-detecting mechanism.

In the case, the showerhead can be rapidly controlled to a desiredtemperature when the showerhead is both heated and cooled.

In addition, in the case, more preferably, the heating mechanism has: aninside heater that heats an inside portion of the showerhead; and anoutside heater that heats an outside portion of the showerhead; and thetemperature detecting mechanism has: an inside-temperature detectingpart that detects a temperature of the inside portion; and anoutside-temperature detecting part that detects a temperature of theoutside portion.

In the case, more preferably, the controller is adapted to control theinside heater in such a manner that a value detected by theinside-temperature detecting part coincides with a set temperature, andto control the outside heater in such a manner that a difference betweena value detected by the outside-temperature detecting part and the valuedetected by the inside-temperature detecting part coincides with zero.

In the case, heat dissipation from the outside portion of the showerheadcan be inhibited, so that more accurate temperature control can beachieved.

In addition, preferably, a thermal-insulating member is arranged on asurface of the showerhead reverse to the chamber.

In the case, during the process, heat dissipation from the showerheadcan be effectively inhibited.

In addition, preferably, the showerhead has: a showerhead body; and acircular supporting part continued upward from on an outside peripheryof the showerhead body; and the supporting part has a rib structure.

In the case, since the portion of the supporting part other than the ribstructure can be made thin, heat dissipation from the supporting partcan be reduced. Thus, temperature controlling performance can be moreenhanced.

In the case, more preferably, an insulating member is arranged on theshowerhead body and inside the supporting part.

In addition, preferably, a circular infilling member and a fixing memberfor fixing the infilling member to the showerhead or the processingcontainer are arranged between the showerhead and the processingcontainer.

In the case, more preferably, a resilient member is interposed betweenthe infilling member and the fixing member. In the case, even whenquartz, ceramics and so on is used as the infilling member, it can beprevented that the infilling member is damaged. In addition, by means ofthe resilient member, the interval between the infilling member and thefixing member can be made uniform.

In addition, preferably, the film-forming apparatus further comprises aplasma-generating unit for generating plasma of the process gas in thechamber.

In addition, preferably, the film-forming apparatus further comprises aninverting mechanism that inverts the showerhead by turning theshowerhead outwardly from the chamber.

In the case, the showerhead is turned outwardly from the chamber, andthus inverted, so that the showerhead can be taken out from the chambersubstantially completely. Thus, maintenance of the showerhead can beconducted very easily.

In addition, this invention is a film-forming apparatus comprising: aprocessing container that defines a chamber; a pedestal arranged in thechamber, on which a substrate to be processed can be placed; ashowerhead provided opposite to the pedestal, which has a large numberof gas-discharging holes; a gas-supplying mechanism that supplies aprocess gas into the chamber through the showerhead; and an invertingmechanism that inverts the showerhead by turning the showerheadoutwardly from the chamber.

According to the invention, the showerhead is turned outwardly from thechamber, and thus inverted, so that the showerhead can be taken out fromthe chamber substantially completely. Thus, maintenance of theshowerhead can be conducted very easily.

Preferably, a circular infilling member and a fixing member for fixingthe infilling member to the showerhead or the processing container arearranged between the showerhead and the processing container.

In the case, more preferably, a resilient member is interposed betweenthe infilling member and the fixing member. In the case, even whenquartz, ceramics and so on is used as the infilling member, it can beprevented that the infilling member is damaged. In addition, by means ofthe resilient member, the clearance between the infilling member and thefixing member can be made uniform.

More preferably, the fixing member is outwardly removable in a statewherein the showerhead is inverted, and the infilling member is upwardlyremovable in a state wherein the fixing member has been outwardlyremoved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a CVD film-forming apparatus of anembodiment according to the present invention;

FIG. 2 is a plan view showing an upper portion of the showerhead of theCVD film-forming apparatus of the embodiment according to the presentinvention;

FIG. 3 is an enlarged sectional view showing a filler portion of theapparatus of FIG. 1;

FIG. 4 is a schematic view showing a portion corresponding to a heatingmechanism in a temperature-controlling unit of the apparatus of FIG. 1;

FIG. 5 is a schematic view showing a preferable control manner inheating and controlling by means of the temperature-controlling unit ofthe apparatus of FIG. 1;

FIG. 6 is a sectional view showing a state wherein a showerhead of theapparatus of FIG. 1 is inverted by an inverting mechanism;

FIG. 7 is an enlarged view of the showerhead of the apparatus of FIG. 1;

FIG. 8 is a sectional view taken along A-A line of FIG. 7;

FIG. 9 is a sectional view taken along B-B line of FIG. 7;

FIG. 10 is a plan view showing a lower plate wherein agas-diffusion-promoting pipe is provided;

FIG. 11 is a sectional view of the lower plate and a middle platewherein the gas-diffusion-promoting pipe of FIG. 10 is attached;

FIG. 12 is a schematic view showing a variant of the portioncorresponding to a heating mechanism of FIG. 4;

FIG. 13 is a schematic view showing a variant of the control manner ofFIG. 5;

FIG. 14 is a sectional view showing a CVD film-forming apparatus ofanother embodiment according to the present invention; and

FIG. 15 is a sectional view showing a variant of the filler member ofFIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a CVD film-forming apparatus for forming a Ti thin filmaccording to an embodiment of the present invention is explainedconcretely.

FIG. 1 is a sectional view showing the CVD film-forming apparatus forforming a Ti thin film according to the embodiment of the presentinvention. FIG. 2 is a plan view showing an upper portion of ashowerhead of the CVD film-forming apparatus of FIG. 1. The film-formingapparatus 1 has a sealed chamber 2 of a substantially cylindrical shapeor a box-like shape. A pedestal 3, on which a semiconductor wafer W asan object to be processed is placed horizontally, is provided in thechamber 2. A pedestal supporting member that protrudes downward isattached at a central bottom of the chamber 2 via a sealing ring. Acylindrical supporting member 4 joined to a bottom surface of thepedestal 3 is fixed to the pedestal supporting member 7. The chamber 2and the pedestal supporting member 7 have heating mechanisms not shown.An electric power source not shown supplies electric power to theheating mechanisms, so that the chamber 2 and the pedestal supportingmember 7 are heated to respective predetermined temperatures.

A ring 5 for stabilizing generation of plasma is provided at an outsideperipheral portion of the pedestal 3. In addition, a heater 6 isembedded in the pedestal 3. An electric power source not shown supplieselectric power to the heater 6, so that the semiconductor wafer W placedon the pedestal 3 as an object to be processed is heated to apredetermined temperature.

A showerhead 10 is arranged opposite to the pedestal 3 at an upperportion of the chamber 2. The showerhead 10 has an upper plate 10 a, amiddle plate 10 b and a lower plate 10 c. The plane shape of theshowerhead 10 is a circle.

The upper plate 10 a has a horizontal portion 10 d that forms ashowerhead body together with the middle plate 10 b and the lower plate10 c, and a circular supporting portion 10 e continued upward from on anoutside periphery of the horizontal portion 10 d. The upper plate 10 ais generally concave. As shown in FIGS. 1 and 2, inside the supportingportion 10 e, ribs 10 f are arranged toward the center of the showerhead10 at regular distance. As the ribs 10 f are formed, while strengthagainst heat deformation of the supporting portion 10 e and supportingstrength of the supporting portion 10 e are enhanced, the other portionof the supporting portion 10 e can be made thin. Thus, heat dissipationfrom the showerhead 10 can be inhibited.

Preferably, each rib 10 f protrudes toward the center by 5 mm or more,in particular 10 mm or more. In addition, preferably, a width of eachrib 10 f is 2 mm or more, in particular 5 mm or more. In addition,preferably, the ribs 10 f are arranged at regular distance.

The upper plate 10 a serves as a base member. An upper portion of anoutside periphery of the circular concave middle plate 10 b is fixed toa lower portion of an outside periphery of the horizontal portion 10 dof the upper plate 10 a by means of screws. An upper surface of thelower plate 10 c is fixed to a lower surface of the middle plate 10 b bymeans of screws. A space 11 a is hermetically formed between a lowersurface of the horizontal portion 10 d of the upper plate 10 a and anupper surface of the middle plate 10 b having a concave portion. Aplurality of grooves are formed radially and uniformly in the lowersurface of the middle plate 10 b. The middle plate 10 b and the lowerplate 10 c are hermetically joined. A space 11 b is formed between theplurality of grooves formed in the lower surface of the middle plate 10b and the upper surface of the lower plate 10 c. In the middle plate 10b, a large number of first gas-passages 12 a, which run from the space11 a toward the lower plate 10 c through a plurality of holes formed inthe middle plate 10 b, and a second gas-passage 12 b, which communicatesnot with the space 11 a but with the space 11 b, are formed. In thelower plate 10 c, a large number of first gas-discharging-holes 13 a,which communicate with the first gas-passages 12 a, and a large numberof second gas-discharging-holes 13 b, which communicates with the space11 b, are formed.

Herein, the inside diameter of each first gas-passage 12 a formed in themiddle plate 10 b is for example 0.5 to 3 mm, preferably 1.0 to 2.0 mm.The inside diameter of each first gas-discharging-hole 13 a formed inthe lower plate 10 c has a two-tier structure, wherein the diameter isfor example φ1.0 to 3.5 mm, preferably φ1.2 to 2.3 mm, at a portion onthe side of the space 11 a and for example φ0.3 to 1.0 mm, preferablyφ0.5 to 0.7 mm, at the other portion on the side of the lower opening.

A first gas-introducing-pipe 14 a and a second gas-introducing-pipe 14 bare connected to an upper surface of the upper plate 10 a. The firstgas-introducing-pipe 14 a communicates with the space 11 a. The secondgas-introducing-pipe 14 b communicates with the second gas-way 12 b ofthe middle plate 10 b and the space 11 b. Thus, a gas introduced fromthe first gas-introducing-pipe 14 a is discharged out from the firstgas-discharging-holes 13 a through the space 11 a and the firstgas-passages 12 a. On the other hand, a gas introduced from the secondgas-introducing-pipe 14 b is introduced into the space 11 b through thesecond gas-passage 12 b and then discharged out from the secondgas-discharging-holes 13 b. That is, the showerhead 10 is a postmix typewherein the gas supplied from the first gas-introducing-pipe 14 a andthe gas supplied from the second gas-introducing-pipe 14 b areindependently supplied into the chamber 2. That is, the gas suppliedfrom the first gas-introducing-pipe 14 a and the gas supplied from thesecond gas-introducing-pipe 14 b are not mixed in the showerhead 10, andsupplied separately.

Herein, FIG. 7 is an enlarged view of the showerhead of FIG. 1. As shownin FIGS. 1 and 7, a sealing ring 10 h can be interposed between a lowersurface of a portion of the upper plate 10 a surrounding a connectingportion with the second gas-introducing-pipe 14 b, which introduces thesecond process gas, and a flange 10 g at a portion of the middle plate10 b forming the second gas-passage 12 b. Thus, it can be prevented moresurely that the respective gases supplied from the firstgas-introducing-pipe 14 a and the second gas-introducing-pipe 14 b mixwith each other.

FIG. 8 is a sectional view taken along A-A line of FIG. 7, and FIG. 9 isa sectional view taken along B-B line of FIG. 7. In FIGS. 7 and 8, anumeral sign 101 indicates bolts. The bolts 101 fasten the middle plate10 b and the lower plate 10 c. Arrows in FIG. 9 indicate flow directionsof gas supplied from the second gas-passage 12 b into the space 11 b.

As shown in FIGS. 7 and 9, slits 212 b as gas-discharging-holes areformed on right and left sides at a lower end of the second gas-passage12 b. The direction in which the slits 212 b are formed may be not onlya right and left direction but also a vertical direction or a diagonaldirection. Instead of the slits 212 b, discharging holes may be formed.The diameter of each discharging hole is preferably 1.0 to 3.0 mm, inparticular 2.0 mm. The number of the discharging holes is optional.

On the other hand, as shown in FIG. 1, a flange 14 is commonly welded torespective base ends of the first gas-introducing-pipe 14 a and thesecond gas-introducing-pipe 14 b, which are connected to the upper plate10 a. An insulating member 24 including a first gas-passage 24 a and asecond gas-passage 24 b is connected to the flange 14. A gas introducingmember 26 including a first gas-passage 26 a and a second gas-passage 26b is connected to the other end of the insulating member 24. Then, thegas introducing member 26 is connected to an upper surface of the lidmember 15. The lid member 15 and the chamber 2 have, respectively, afirst gas-passage 15 a, 2 a and a second gas-passage 15 b, 2 b. Thefirst gas-passages 24 a, 26 a, 15 a and 2 a and the second gas-passages24 b, 26 b, 15 b and 2 b from the flange 14 to the chamber 2 are,respectively, communicated in series, and sealing rings such as O-ringsare interposed at connecting portions thereof. In addition, a first gaspipe 25 a is connected to the first gas-passage 2 a in the chamber 2,and a second gas pipe 25 b is connected to the second gas-passage 2 b.And the respective base ends of the gas pipes 25 a and 25 b areconnected to a gas supplying part 30.

The gas supplying part 30 has: a ClF₃ gas source 31 that supplies ClF₃gas, which is a cleaning gas; a TiCl₄ gas source 32 that supplies TiCl₄gas, which is a film-forming gas; an Ar gas source 33 that supplies Argas, which is a carrier gas; a H₂ gas source 34 that supplies H₂ gas,which is a reduction gas; and a NH₃ gas source 35 that supplies NH₃ gas,which is used for nitriding a Ti film. The ClF₃ gas source 31, the TiCl₄gas source 32 and the Ar gas source 33 are respectively connected to gaspipes 36, 37 and 38. The gas pipes 36, 37 and 38 are connected to thesecond gas pipe 25 b. The H₂ gas source 34 and the NH₃ gas source 35 arerespectively connected to gas pipes 39, 40. The gas pipes 39 and 40 areconnected to the first gas pipe 25 a.

Thus, the respective gases from the ClF₃ gas source 31, the TiCl₄ gassource 32 and the Ar gas source 33 arrive in the second gas-passage 12 bof the middle plate 10 b of the showerhead 10, through the gas pipe 25b, the second gas-passages 2 b, 15 b, 26 b and 24 b of the aboverespective members and the gas-introducing-pipe 14 b. Then, therespective gases are introduced into the space 11 b, and discharged outfrom the second gas-discharging-holes 13 b of the lower plate 10 c.

The respective gases from the H₂ gas source 34 and the NH₃ gas source 35are introduced in the space 11 a of the showerhead 10, through the gaspipe 25 a, the first gas-passages 2 a, 15 a, 26 a and 24 a of the aboverespective members and the gas-introducing-pipe 14 a. Then, therespective gases are discharged out from the first gas-discharging-holes13 a of the lower plate 10 c through the first gas-passages 12 a of themiddle plate 10 b.

Therefore, during a film-forming process, the TiCl₄ gas and the H₂ gasare not mixed with each other on the way to be supplied, but mixed afterdischarged into the chamber 2. Plasma is generated, a predeterminedreaction is produced, and a Ti film is deposited on the semiconductorwafer W. A mass-flow controller 41 and a pair of opening/closing valves42 and 43, between which the mass-flow controller 41 is sandwiched, areprovided in each gas pipe 36, 37, 38, 39, 40 from each gas source. Thegas supplying part 30 includes an N₂ gas source, another pipe, andanother opening/closing valve and so on, which are not shown. Inaddition, for example, the gases supplied into the spaces 11 a and 11 bmay be changed by changing the gas sources connected to the firstgas-passage 26 a and the second gas-passage 26 b, which are formed inthe gas introducing member 26.

A lid member 15 having an opening is mounted on an upper side of thechamber 2. A circular insulating member 16 is mounted on an insideperipheral portion of the lid member 15. Then, the supporting portion 10e of the upper plate 10 a is supported by the insulating member 16. Anupper portion of the supporting portion 10 e is covered by a circularinsulating member 21 for the purpose of heat insulation. The insulatingmember 21 is supported by the lid member 15. The insulating member 16has an effect of electrical insulation between the showerhead 10 and thechamber 2 and an effect of heat (thermal) insulation. Sealing rings suchas O-rings are respectively interposed between the chamber 2 and the lidmember 15, between the lid member 15 and the insulating member 16, andbetween the insulating member 16 and the supporting portion 10 e. Thus,a sealed state is formed.

An inside heater 17 is arranged on an upper surface of the horizontalportion 10 d of the upper plate 10 a, correspondingly to the wholesurface of the semiconductor wafer W placed on the pedestal 3. Forexample, the inside heater 17 may be formed by sandwiching a thinplate-like heater member between mica insulating plates. A circular(doughnut-like) outside heater 18, for example a sheath heater, isfitted so as to surround an outside periphery of the inside heater 17.(FIG. 14 shows a structure wherein the same heater as the inside heater17 is arranged as an outside heater.) These heaters function as elementsof a showerhead-temperature controlling unit, which is explained below.

A space 19 is provided above the inside heater 17. A heat insulatingmember 20 is arranged above the space 19. The heat insulating member 20may be a ceramics resin such as Al₂O₃ or the like. The heat insulatingmember 20 has a cooling-gas passage 20 a and a discharging port 20 b. Adry-air supplying pipe 61 a for cooling an inside portion is connectedto an upper portion of the cooling-gas passage 20 a. A dry-air supplyingpipe 61 b for cooling an outside portion is arranged above thesupporting portion 10 e of the upper plate 10 a. The pipe 61 b has apipe portion 61 c along an inside periphery of the insulating member 21.A large number of jetting-holes for jetting out dry air are uniformlyand downwardly provided at the pipe portion 61 c. The jetted dry air issupplied into a gap between the insulating member 16 and the heatinsulating member 20 and its vicinity, so as to cool the outside heaterand its vicinity.

A power supply line 45 is connected to an upper surface of the upperplate 10 a of the showerhead 10. The power supply line 45 is connectedto a high-frequency electric power source 47 via a matching unit 46.Then, a high-frequency electric power is supplied from thehigh-frequency electric power source 47 to the showerhead 10. Thus, ahigh-frequency electric field is formed, the process gas supplied intothe chamber 2 is made plasma, and the film-forming reaction is promoted.

A circular filler 48 made of quartz is provided so as to prevent thatplasma is generated around a lower portion of the showerhead 10,especially in a space surrounded by lateral surfaces of the upper plate10 a, the middle plate 10 b and the lower plate 10 c, a lower surface ofthe insulating member 16, a lower surface of the lid member 15 and aside wall of the chamber 2. As shown in FIG. 3, the filler 48 has aconcave portion 48 a at an outside portion thereof. Convex portions 49 aof a plurality of supporting members 49 fastened to the lid member 15 bymeans of screws are fitted in the concave portion 48 a to support thefiller 48. An elastic (resilient) member 50 such as a fluoro rubber isinterposed between a lateral surface of the concave portion 48 a of thefiller 48 and a lateral surface of each convex portion 49 a of eachsupporting member 49. Because of the elastic member 50, centering of theshowerhead 10 can be easily achieved and the filler 48 can be simplyattached and removed. In addition, breakage of the filler 48 caused bythermal expansion and contraction can be prevented. An elastic(resilient) member 51 is interposed between the filler 48 and the lidmember 15. The elastic member 51 also has a function of preventing thebreakage of the filler 48.

An exhaust pipe 52 is connected to a side wall at a base portion of thecylindrical pedestal supporting member 7 attached at a base portion ofthe chamber 2. An exhaust unit 53 is connected to the exhausting pipe52. Thus, the chamber 2 can be evacuated. A unit that traps unreactedmaterials and/or by-products is not shown but provided on an upstreamside with respect to the exhausting unit 53. The chamber 2 can bevacuumed to a predetermined vacuum level by driving the exhausting unit53. In addition, a sealed box 23 is provided over the lid member 15. Anexhausting port 54 is provided at an upper portion of the sealed box 23.Inside heated dry air and outside heated dry air in the sealed box 23are adapted to be exhausted from the exhausting port 54.

The CVD film-forming apparatus 1 according to the embodiment has ashowerhead-temperature controlling unit 60 that controls a temperatureof the showerhead 10. The showerhead-temperature controlling unit 60 isexplained hereinafter.

As main elements, the showerhead-temperature controlling unit 60 has:the inside heater 17 and the outside heater 18, which are describedabove as a heating mechanism; the dry-air supplying pipes 61 a and 61 bfor supplying dry air as a cooling mechanism; a temperature-detectingmechanism consisting of thermocouples 65 a, 65 b, 66 a and 66 b thatmonitor temperatures of the inside heater 17, the outside heater 18 andthe lower plate 10 d of the showerhead 10; and a controller 62 thatcontrols the above elements.

As enlargedly shown in FIG. 4, an electric power source 63 is connectedto the inside heater 17, and an electric power source 64 is connected tothe outside heater 18. At a position corresponding to the inside heater17 arranged at the inside portion on the upper plate 10 a of theshowerhead 10, the thermocouple 65 a for detecting the temperaturecontacts with an insulating sheet 131 of high thermal conductivity onthe upper plate, and the thermocouple 65 b contacts with the inside ofthe lower plate. At a position corresponding to the outside heater 18arranged at the outside portion on the upper plate 10 a, thethermocouple 66 a for detecting the temperature of the outside portionof the upper plate 10 a contacts with the inside of the upper plate andthe thermocouple 66 b for detecting the temperature of the outsideportion of the lower plate 10 c contacts with the inside of the lowerplate. Each thermocouple 65 a, 65 b, 66 a, 66 b may be a plurality ofthermocouples. In addition, provided is an inside-temperature controllerthat controls the temperature by means of a PID control to the output ofthe inside heater 17, based on an instruction of the controller 62 and asignal detected by the thermocouple 65 a or 65 b, and provided is anoutside-temperature controller 68 that controls the temperature by meansof a PID control to the output of the outside heater 18 or the like,based on an instruction of the controller 62 and a signal detected bythe thermocouple 66 a or 66 b. Thus, when the showerhead 10 is heated,temperature control of the showerhead 10 can be achieved by thetemperature controllers 67 and 68.

On the other hand, the dry air supplied from the dry-air supplying pipe61 a is introduced into the space through the cooling-gas passage 20 aof the heat insulating member 20, as a cooling material. The dry airtakes heat emitted from the inside heater 17 into the space 19, flowsthrough the exhausting port 20 b, and is exhausted from the exhaustingport 54 of the sealed box 23 provided on the upper portion of the lidmember 15. The dry air supplied from the dry-air supplying pipe 61 b isdischarged out from the discharging-holes on the lower side of the pipe,takes heat in the outside portion of the showerhead including theoutside heater 18 or the like, and is exhausted from the exhausting port54 of the sealed box 23. Air operation valves 69 a and 69 b arerespectively provided in the dry-air supplying pipes 61 a and 61 b. Theair operation valves 69 a and 69 b are controlled by the controller 62.

When the showerhead is heated while the showerhead controlling unit 60is used, a preferable temperature control can be achieved in accordancewith a control shown in FIG. 5. In the control shown in FIG. 5, a settemperature is set at the controller 62. Then, the temperaturecontroller 67 controls the output of the inside heater 17 in such amanner that a temperature detected by the thermocouple 65 a or 65 bcoincides with the set temperature. The value detected by thethermocouple 65 a or 65 b is also outputted to the temperaturecontroller 68 via the controller 62. Then, the temperature controller 68controls the output of the outside heater 18 in such a manner that thedifference between a temperature detected by the thermocouple 66 a or 66b at the position corresponding to the outside heater 18 and atemperature detected by the thermocouple 65 a or 65 b at the positioncorresponding to the inside heater 17 coincides with zero. Therefore,the temperature of the outside portion of the showerhead 10 and thetemperature of the inside portion of the showerhead 10 are controlled tobe substantially the same.

The upper surface of the upper plate 10 a of the showerhead 10 and aportion above it are exposed to atmospheric air. The thermocouples 65 band 66 b of the showerhead-temperature controlling unit 60 are arrangedin the showerhead, which can be a vacuum. However, the other elementsare arranged in the atmospheric air.

In addition, as shown in FIG. 2, the showerhead 10 can be invertedoutwardly from the chamber 2 by an inverting mechanism 80 having a hingemechanism. Thus, as shown in FIG. 6, the showerhead 10 can be positionedsubstantially completely outside the chamber 2 in such a manner that thegas-discharging surface is directed upward. Thus, maintenance of theshowerhead 10 can be very easily conducted. Concretely, from the stateshown in FIG. 6, the plurality of supporting members 49 can be easilytaken out outwardly by removing the fastening screws (arrow (1)). Afterthe supporting members 49 are taken out, the filler 48 can be easilytaken out upwardly (arrow (2)). Then, after the filler 48 is taken out,maintenance of the showerhead 10 itself can be conducted. For example,the lower plate 10 c and the middle plate 10 b can be easily taken outupwardly (arrow (3)). After the showerhead 10 is inverted, it ispreferable that the showerhead 10 is held at a position inverted by 180degrees. It is sufficient that the inverted degrees are around 180degrees. In order to hold the showerhead 10 at such position, a gasspring or the like can be used.

Next, a processing operation of the CVD film-forming apparatus 1 asstructured above is explained. At first, before a Ti thin film is formedon a semiconductor wafer W, a pre-coated film is formed on the surfacesof the showerhead 10 and the pedestal 3 and so on in accordance with thefollowing steps. First, environs of the chamber 2, the heater 6 of thepedestal 3, and the inside and outside heaters 17 and 18 of theshowerhead 10 are heated. Then, the chamber 2 is exhausted by thedischarging unit 53, a predetermined gas is introduced into the chamber2 at a predetermined flow rate, and the inside of the chamber 2 becomesa predetermined pressure. Then, a film-forming gas, which includes H₂gas, Ticl₄ gas and other gases, is introduced into the chamber 2 at apredetermined flow rate, and a high-frequency electric power is suppliedfrom the high-frequency electric power source 47 to the showerhead 10,so that plasma is generated in the chamber 2. Thus, a Ti film isdeposited on the showerhead 10 and the pedestal 3 and so on. Then, thesupply of the electric power from the high-frequency electric powersource 47 and the supply of the TiCl₄ gas are stopped. Then, NH₃ gas andother gases are supplied at predetermined flow rates, and again thehigh-frequency electric power is supplied from the high-frequencyelectric power source 47 to the showerhead 10, so that plasma isgenerated. Thus, a surface of the deposited Ti film is nitrided, so thata stable pre-coated film is formed on the showerhead 10 and pedestal 3and so on. After the nitriding process is completed, the supply of theelectric power from the high-frequency electric power source 47 and thesupply of the NH₃ gas are stopped.

After the pre-coating process is completed, a gate valve not shown isopened, and a semiconductor wafer W is conveyed into the chamber 2 andplaced onto the pedestal 3. Then, the H₂ gas, the Ticl₄ gas and theother gases are supplied at predetermined flow rates, and ahigh-frequency electric power is supplied from the high-frequencyelectric power source 47 to the showerhead 10, so that plasma isgenerated in the chamber 2. Thus, a Ti film is deposited on thesemiconductor wafer W. Then, the supply of the electric power from thehigh-frequency electric power source 47 and the supply of the TiCl₄ gasare stopped. Then, the NH₃ gas and the other gases are supplied atpredetermined flow rates, and again the high-frequency electric power issupplied from the high-frequency electric power source 47 to theshowerhead 10, so that plasma is generated. Thus, the Ti film depositedon the semiconductor wafer W is nitrided. After the nitriding process iscompleted, the supply of the electric power from the high-frequencyelectric power source 47 and the supply of the NH₃ gas are stopped.After the film-forming process is completed as described above, theprocessed semiconductor wafer W is conveyed out from the chamber 2,another semiconductor wafer W to be successively processed is conveyedinto the chamber, and the same film-forming process is conducted to thelatter semiconductor wafer W.

After the film-forming process is conducted to a predetermined number ofsemiconductor wafers W, the pedestal 3 and the showerhead 10 are cooledto a predetermined temperature, and ClF₃ gas as a cleaning gas issupplied into the chamber 2 in order to conduct a cleaning process.

In the series of processes, in accordance with the embodiment, thefollowing effects can be achieved because the showerhead 10 is providedwith the showerhead-temperature controlling unit 60.

In the pre-coating process and the film-forming process, unreactedproducts TiCl_(x) (x=1, 2, 3) may be formed. The TiCl_(x) has to bevolatilized in order to form a stable film on the showerhead. For thatpurpose, a temperature not lower than 425 C.°, preferably not lower than500° C., is necessary. As the conventional showerhead is passivelyheated by the heater in the pedestal, there is no certification of thatthe conventional showerhead is heated to or over 425° C. Thus,conventionally, there were possibilities that a stable pre-coated filmmay not be formed on the showerhead. However, in the embodiment, theshowerhead is provided with the showerhead-temperature controlling unit60, so that the showerhead 10 can be actively heated to or over 425° C.In addition, by supplying a gas including the NH₃ gas so as to reduceand nitride TiCl_(x), a stable pre-coated film can be surely formed onthe showerhead 10.

In addition, when the inside of the chamber 2 is heated to afilm-forming temperature, if the showerhead 10 is heated only by radiantheat from the pedestal 3 like a conventional manner, it takes a longtime for the temperature of the showerhead 10 to become stable at apredetermined heating temperature. However, according to the embodiment,in addition to being passively heated by the heater 6 of the pedestal 3,the showerhead 10 is in advance actively heated by the heaters 17 and 18that are elements of the showerhead-temperature controlling unit 60.Thus, within a shorter time, the whole showerhead 10 is heated, so thatthe temperature of a surface of the lower plate of the showerhead 10 canbe stabilized to a constant temperature. Thus, the temperature in thechamber 2 can be stabilized to a predetermined temperature within ashort time. As described above, as the temperature of the showerhead 10is controlled uniformly, the Ti film can be formed uniformly on thesemiconductor wafer W. Especially, when a semiconductor wafer isenlarged to 300 mm and thus the apparatus is also enlarged, the aboveeffect is remarkable.

During an idling state, the high-frequency electric power source isturned off. Thus, conventionally, in order to maintain the temperatureof the showerhead 10 at a predetermined temperature, the temperature ofthe heater in the pedestal was set higher. On the other hand, accordingto the embodiment, as the temperature of the showerhead 10 is controlledby the showerhead-temperature controlling unit 60, the temperature ofthe showerhead 10 can be maintained and stabilized at a predeterminedtemperature, even during an idling state.

For a cleaning process, the temperature of the showerhead 10 has to belowered from the film-forming temperature to a cleaning temperature of200 to 300° C. Conventionally, heat-radiating performance of theshowerhead was so poor that it took a long time for the temperature tofall down. However, according to the embodiment, dry air as a coolingmedium is supplied to the upper portion of the showerhead 10 through thedry-air supplying pipes 61 a and 61 b by the showerhead-temperaturecontrolling unit 60, in order to cool the showerhead. Thus, the insidetemperature of the chamber 2 can be fast lowered to a cleaningtemperature.

In the unit of the embodiment, the upper part of the upper plate 10 a ofthe showerhead 10 is exposed to atmospheric air. Thus, almost all theelements of the showerhead-temperature controlling unit 60 can bedisposed inside atmosphere. Therefore, it is easy to handle theshowerhead-temperature controlling unit 60.

In addition, in the embodiment, the inside heater 17 and the outsideheater 18 are provided as a heating mechanism of theshowerhead-temperature controlling unit 60, in order to achieve atwo-zone control. Then, as shown in FIG. 4, the output of the insideheater 17 is controlled by the temperature controller 67 in such amanner that a temperature detected by the thermocouple 65 a or 65 bcoincides with a set temperature, and the output of the outside heater18 is controlled by the temperature controller 68 in such a manner thatthe difference between a temperature detected by the thermocouple 66 aor 66 b located correspondingly to the outside heater 18 and thetemperature detected by the thermocouple 65 a or 65 b locatedcorrespondingly to the inside heater 17 coincides with zero, so that theinside portion and the outside portion of the showerhead 10 arecontrolled to be always at the same temperature. Thus, heat dissipationfrom the outside portion of the showerhead 10 can be inhibited, so thattemperature controlling performance can be enhanced. Especially, whenthe size of a semiconductor wafer is enlarged to 300 mm, as heat tendsto be dissipated from the outside portion of the showerhead 10, theabove two-zone control is more effective.

At the maintenance of the showerhead 10, the showerhead 10 is invertedoutwardly from the chamber 2 by the inverting mechanism 8. Thus, asshown in FIG. 6, the maintenance of the showerhead 10 can be conductedwhile the gas-discharging surface of the showerhead 10 is directedupward. That is, the maintenance of the showerhead 10 can be conductedvery easily. Concretely, from the state shown in FIG. 6, the pluralityof supporting members 49 are taken out outwardly. Then, the filler 48 istaken out upwardly. Then, the lower plate 10 c and the middle plate 10 bof the showerhead 10 are taken out upwardly. As described above, eachoperation for taking-out each element is so easy that the maintenance ofthe showerhead 10 can be conducted very easily.

This invention is not limited to the above embodiment, but may bevariably modified within a scope of spirit of the invention. Forexample, although the film-forming process of a Ti film is explained inthe above embodiment, this invention is not limited thereto, butapplicable to a CVD film-forming process of another film such as a TiNfilm. In addition, although the case wherein the plasma is generated isexplained, the plasma is not necessary. The showerhead-temperaturecontrolling unit is also not limited to the above structure. Thecontrolling method is also not limited to the above method. For example,although the dry air is used as a cooling medium, another gas such as Aror N₂ can be also used. If plasma is not used, liquid such as water orcoolant can be used as a cooling medium. In addition, although theprocess to the semiconductor wafer is explained, this invention is notlimited thereto, but also applicable to a process to another substratesuch as a Liquid-Crystal-Display glass substrate.

Next, a variant of the above embodiment is explained in detail.

As shown in FIG. 9, in the above embodiment, the second gas-supplyingportion 12 communicating with the second gas-passage 12 b is arranged inthe substantially central portion of the space 11 b formed below themiddle plate. The openings 12 c are formed on the lateral sides of thegas-supplying portion 12. Thus, the gas supplied through the secondgas-passage 12 b, which communicates with the second gas-supplying pipe14 b and is formed above the middle plate, is discharged from theopenings 12 c of the gas-discharging portion 12 and directly diffusedinto the space 11 b.

However, according to that manner, the gas supplied through the secondgas-passage 12 b may not be sufficiently uniformly diffused into thespace 11 b of the middle plate 10 c.

Then, it is preferable that one or more gas-diffusion promoting pipesare connected to the openings 12 c of the second gas-discharging portion12 arranged in the substantially central portion of the space 11 b.

In the case of the middle plate 10 c shown in FIG. 10, a substantiallyH-shaped gas-diffusion promoting pipe 110 is arranged in the space 11 bbelow the middle plate 10 c in order to uniformly diffuse the secondgas. The central portion of the substantially H-shaped gas-diffusionpromoting pipe 110 is connected to and fitted in the secondgas-discharging portion 12. Gas-discharging holes 110 a are formed atfour tip portions of the gas-diffusion promoting pipe 110. Thegas-diffusion promoting pipe 110 is formed integratedly by welding.Supporting pillars 110 b that supports the gas-diffusion promoting pipe110 are fixed to the middle plate 10 b and the upper surface of thelower plate 10 c, in order to prevent motion of the gas-diffusionpromoting pipe 110.

In this case, the gas-discharging holes 110 a formed at the respectivetip portions are open toward the upper plate, so that the gas suppliedthrough the second gas-discharging portion 12 can be sufficientlyuniformly diffused into the space 11 b. Arrows in FIG. 10 schematicallyshow flows of the gas supplied from the gas-discharging holes 110 a intothe space 11 b. The shape, the orientation and the position of thegas-diffusion promoting pipe 110, the number of gas-discharging holes110 a and the manner of openings are not limited, if the gas suppliedthrough the second gas-passage 12 b can be diffused sufficientlyuniformly into the space 11 b. For example, the gas-discharging holes110 a may be formed to open to a lateral direction. The gas-dischargingholes 110 a may be formed uniformly on the way to the tip ends of thepipe, preferably uniformly in the space 11 b.

FIG. 11 shows a sectional view of the middle plate 10 b attached to thelower plate 10 c and the gas-diffusion promoting pipe 110 shown in FIG.10. FIG. 11 shows a section piercing a central pipe 110 c of thegas-diffusion promoting pipe 110 basically, but shows a section piercinga gas-discharging hole 110 a at a right-end portion of the gas-diffusionpromoting pipe 110.

FIGS. 12 and 13 show a variant regarding the control system. FIG. 12 isa schematic view showing the variant at a portion corresponding to theheating mechanism of FIG. 4, and FIG. 13 is a view showing the variantof the controlling manner of FIG. 5.

In the case shown in FIGS. 12 and 13, noise filters 120 are providedbetween the control system and the respective thermocouples 65 a, 65 b,66 a and 66 b, and between the control system and the respective heaters17 and 18. Preferably, they are arranged nearer to the control system.Providing the noise filters 120 like this is effective in removingnoises from the high-frequency electric power source 47 to improve thecontrolling performance.

In a variant shown in FIG. 14, instead of the circular outside heater 18having a circular section, a flat doughnut-like outside heater 118 isprovided. Like this, the shape of the heater is not limited inparticular.

In the variant shown in FIG. 14, an insulating sheet 131 is formedbetween the inside heater 17 and the upper plate 10 a, and an insulatingsheet 132 is similarly formed between the outside heater 118 and theupper plate 10 a. The thickness of the respective insulating sheets 131is a degree not affected by noises, for example 0.5 mm to 1.0 mm. Theupper plate 10 a functions as an electrode for generating plasma, sothat the insulating sheets 131 and 132 are preferably thick in order toinhibit effects of the noises that the heaters receive. Herein, theinsulating sheets 131 and 132 have to have high heat conductivity andhigh heat resistance. Thus, ceramics such as aluminum nitride issuitable as a material of the insulating sheets 131 and 132.

In a variant shown in FIG. 15, instead of the elastic member 50 made ofa fluorine rubber or the like, a corrosion-resisting metal spring, forexample an elastic member 150 made of a Ni-alloy such as inconel, isprovided. Like this, the manner of an elastic member interposed betweenthe lateral surface of the concave portion 48 a of the filler 48 and thelateral surface of the convex portion 49 a of the supporting member 49is not limited in particular.

Herein, regarding during the idling state and during the cleaningprocess, the respective features of temperature control according tothis invention and prior art are shown in the following table.

Temperature Temperature of of showerhead pedestal Operation Prior art470~480° C. 640~650° C. Temperature of pedestal has to be raised notlower than film-forming temperature Invention 500° C. 640° C.Temperature of showerhead is directly controlled

1. A film-forming apparatus comprising: a chamber in which a substrateto be processed is processed, a stage arranged in the chamber, on whichthe substrate to be processed can be placed, a heater buried in thestage, and a showerhead provided opposite to the stage, which has alarge number of gas-discharging holes, a lid member mounted on an upperpart of the chamber, which has an opening, a showerhead-temperaturecontrolling unit arranged in an upper part of the showerhead, whichcontrols a temperature of the showerhead, chamber gas passages formed atthe chamber, which respectively supply a film-forming gas and a cleaninggas, lid-member gas passages formed at the lid member, whichrespectively communicate with the chamber gas passages, gas-introducingpipes connected to the showerhead, which respectively communicate withthe chamber gas passages and the lid-member gas passages and supply thefilm-forming gas and the cleaning gas into the showerhead, aplasma-generating unit for generating plasma of the film-forming gas inthe chamber, a discharging unit for exhausting the chamber, a circularinsulating member for insulating the showerhead from the chamber, aninfilling member for infilling a space surrounded by a periphery of theshowerhead and a side wall of the chamber, for preventing plasma frombeing formed at the space, a fixing member for fixing the infillingmember, and a gas-spring type of inverting mechanism that inverts theshowerhead by turning the showerhead outwardly from the chamber.
 2. Afilm-forming apparatus according to claim 2, wherein theshowerhead-temperature controlling unit includes: an inside heaterarranged correspondingly to the substrate to be processed, and anoutside heater arranged so as to surround the inside heater.
 3. Afilm-forming apparatus according to claim 1, further comprising anotherinsulating member having insulating-member gas passages respectivelyconnected to the gas-introducing pipes, and a gas-introducing memberhaving gas-introducing-member gas passages respectively connected to theinsulating-member gas passages.
 4. A film-forming apparatus according toclaim 2, further comprising another insulating member havinginsulating-member gas passages respectively connected to thegas-introducing pipes, and a gas-introducing member havinggas-introducing-member gas passages respectively connected to theinsulating-member gas passages.
 5. A film-forming apparatus according toclaim 1, further comprising an heat insulating member arranged above theheaters via an atmospheric air space.
 6. A film-forming apparatusaccording to claim further comprising an heat insulating member arrangedabove the heaters via an atmospheric air space.
 7. A film-formingapparatus according to claim 3, further comprising an heat insulatingmember arranged above the heaters via an atmospheric air space.
 8. Afilm-forming apparatus according to claim 4, further comprising an heatinsulating member arranged above the heaters via an atmospheric airspace.
 9. A film-forming apparatus according to claim 1, wherein theshowerhead has: an upper plate, a middle plate, and a lower plate, afirst space is formed between the upper plate and the middle plate, anda second space is formed between the middle plate and the lower plate.10. A film-forming apparatus according to claim 2, wherein theshowerhead has: an upper plate, a middle plate, and a lower plate, afirst space is formed between the upper plate and the middle plate, anda second space is formed between the middle plate and the lower plate.11. A film-forming apparatus according to claim 3, wherein theshowerhead has: an upper plate, a middle plate, and a lower plate, afirst space is formed between the upper plate and the middle plate, anda second space is formed between the middle plate and the lower plate.12. A film-forming apparatus according to claim 4, wherein theshowerhead has: an upper plate, a middle plate, and a lower plate, afirst space is formed between the upper plate and the middle plate, anda second space is formed between the middle plate and the lower plate.13. A film-forming apparatus according to claim 1, wherein the infillingmember consists of quartz.